the AST (Assenmacher Specialty Tools) line of diagnostic tools.
They have a model called the 'Retreiver'. At $2k street price, it with the 5704F cartrirdge does all DTCs plus live data and adaptation.
http://www.asttool.com/html/cars/mercedes/diagnosis/dia1.html
AST has just introduced a version that works with a laptop.
http://www.asttool.com/html/new_tools/diagnosis/pcr/pcr_main.html